1) over a wide pressure range has larger suction capacity;

(2) has a good symmetry of the rotor, so less vibration, smooth operation. Rotors and between the gap between rotor and housing, without lubrication, friction loss, driving power can be greatly reduced, thereby achieving higher speeds;

(3) in the pump Chamber without need of oil seal and lubrication, reducing oil vapor contamination of vacuum systems;

(4) in the pump Chamber without compression and without exhaust valve. Structure is simple and compact, not sensitive to dust and water vapor in a gas;

(5) the compression is low, to hydrogen pumping effect;

(6) the rotor surface is cylindrical shape is more complex curves, processing and inspection more difficult.